Trimet Aluminium has commissioned a new cathode heating unit in the Essen aluminium smelter.
This customized plant with four cathode furnaces and connected ladle and mould firing increases energy efficiency and enhances occupational safety. In addition, working steps have been reduced and are more ergonomic. “Modernization of cathode treatment marks a further stage in the process of making our production locations fit for the future. We are increasing energy efficiency, lowering CO2 emissions and enhancing occupational safety,” says Andreas Lützerath, a member of the executive board of Trimet.
Innovative construction of the cathode heating station
Electrolysis cells for aluminium production are relined for this purpose in the cathode repair workshop. This involves casting of cathode bars into cathode blocks using cast iron. The cathode blocks, which consist of graphite, are heated in the heating unit to minimize the temperature shock when pouring the cast iron. However, the preheating temperature should not exceed 500 °C to prevent the blocks from igniting. Simultaneously, the cathode bars placed in should achieve a temperature exceeding 600 °C. This technological challenge is solved by flameless line burners in the new plant that heat the cathode iron from above. Intelligent control of hot combustion gases means that additional undergrate firing can be dispensed with.
The innovative design integrates the line burners in the furnace lids. This minimizes heat loss, limits heat radiation for employees to 40 °C and lowers both the energy requirement and CO2 emissions by two thirds. Moreover, the new plant is considerably quieter than its predecessor.
Trimet has also simplified handling and operation in the cathode repair workshop through simultaneous renewal of ancillary equipment. Introduction of a combined transfer and casting ladle enables multiple pouring of molten cast iron during the casting process. Insulation of the ladle protects personnel from excessive heat and enhances energy efficiency.